In general, a washing machine is a device in which in a state that washing water is supplied to the interior of a drum in which the laundry has been input to be placed, the drum is rotated in a forward direction or in a backward direction to allow the laundry within the drum to collide with the washing water so as to wash dirt or stain off the laundry by using energy generated according to the collision between the laundry and the washing water.
FIG. 1 illustrates the configuration of a general washing machine. As shown in FIG. 1, the general washing machine includes a main body 5, a tub 3 installed at the interior of the main body 5 and keeping washing water in storage, a drum 9 rotatably installed within the tub 3 and receiving the laundry inputted thereto, driving motors 130 and 140 configured to rotate the drum 9, a rotational shaft 150 configured to transfer a rotational force of the driving motors 130 and 140 to the drum 9, a bearing 11 supporting the rotational shaft 150, a detergent supply device 30 configured to supply water mixed with a detergent to the tub 3, a water supply device 20 including a plurality of valves for supplying water to the detergent supply device 30 or interrupting water supply to the detergent supply device 30, and a drain pump 40 configured to pump water stored in the tub 3 to drain it out. A stop spring 4 is installed between an inner side of an upper surface of the main body 5 and an upper side of an outer circumferential surface of the tub 3, supporting the tub 3, and a friction damper 10 is installed between an inner side of a lower surface of the main body 5 and a lower side of an outer circumferential surface of the tub 3, to attenuate vibration of the tub 3. A plurality of lifters 9a are installed at the inner side of the drum 9 in order to stir the laundry.
The driving motors 130 and 140 include a stator 130 and a rotor 140 having a permanent magnet and rotating on an outer circumferential surface of the stator 130. The stator 130 is fastened to a rear wall of the tub 3 and the rotor 140 is fastened to a rear end portion of the rotational shaft 150.
As shown, the driving motors 130 and 140 are disposed at an outer side of the tub 3 and rotate the drum installed at the inner side of the tub. Thus, the presence of the driving motors between the rear wall of the tub 3 and the rear surface of the main body hampers the use of the internal space of the main body 5 of the washing machine, resulting in the limitation in the floor area ratio of the tub 5 or the drum 9, namely, in the washing capacity allowed by the washing machine, when the size of the main body 5 is fixed. In addition, because the driving motor causing noise and vibration of the washing machine is exposed to outside, noise and vibration of the washing machine is further increased.